-LRB- CNN -RRB- -- One 12-year-old Virginia boy was playing baseball when it happened .

Lightning strikes Las Vegas in 2006 . Already this month 11 people have been killed by lightning in the U.S. .

The same week , a 33-year-old man was struck while jogging in Texas , a 70-year-old California woman was hit while doing yard work and a Kentucky man , 44 , fell victim while waiting under a tree for a ride .

They are among 11 people killed already this month by lightning strikes in the United States , according to the National Weather Service .

`` Lightning is very random in terms of fatalities , '' National Weather Service lightning safety expert John Jensensius told CNN . `` We normally see a good amount of lightning in June , but this is unusually high . There really is no good explanation of why that 's the case . ''

Six of the 15 lightning-strike deaths in the U.S. so far this year occurred in California , Texas and Florida , with the rest scattered through the South , Midwest and West . No deaths have occurred in the Northeast so far , `` likely due to the cool , damp pattern we 've seen in New England , '' Jensensius said . `` There have been less severe thunderstorms there . ''

Summer is the deadliest season for lightning strikes because of the frequency of thunderstorms and the fact that more people are outdoors . This week , the first official week of summer , marks `` Lightning Safety Awareness Week '' for the National Oceanic and Atmospheric Administration -LRB- NOAA -RRB- .

The agency 's message is `` When Thunder Roars , Go Indoors . '' That 's because all the people killed by lightning in the U.S. so far this year -- and the 28 killed in 2008 -- were outdoors . Taking shelter under trees offers little safety -- nearly one-third of the people killed by lightning last year were under a tree when they were hit .

More than 400 people in the U.S. are hit by lightning each year , according to the National Weather Service . Lightning , on average , kills more people than hurricanes and tornadoes combined -LRB- among all weather-related fatalities , only floods kill more -RRB- . While not all injuries result in death , many victims are left with devastating and permanent disabilities .

You may remember that as a child you were told to count the seconds between a lightning flash and thunder to see how far away the lightning was . But by the time you calculate it , it may be too late . Sometimes thunder and lightning can happen simultaneously .

Despite its `` Sunshine State '' nickname , Florida receives more cloud-to-ground lightning than any other state in the country , according to data from NASA satellites .

But Florida does not receive the most lightning in the world . According to NASA research , that dubious honor goes to the Democratic Republic of Congo , with 158 strikes per square kilometer each year . Thunderstorms occur in Central Africa year-round .

Here are some commonly asked lightning questions :

How powerful is lightning ?

According to the National Weather Service , `` each spark of lightning can reach over five miles in length , soar to temperatures of approximately 50,000 degrees Fahrenheit and contain 100 million electrical volts . ''

Can wearing rubber shoes protect you from lightning ?

No . That 's a myth , and there are lots of them out there . For facts on lightning safety , visit http://www.lightningsafety.noaa.gov/ .

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Eleven people have been killed already this month by lightning strikes in the U.S.

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All the U.S. 's 15 lightning deaths this year occurred in the South , Midwest and West

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Summer is the deadliest season for lightning because of the frequency of storms

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This week , the first official one of summer , is Lightning Safety Awareness Week